1. Field of the Invention
This invention relates to a record bearing medium loading device for loading a tape-shaped record bearing medium in a predetermined position.
2. Description of the Related Art
As the loading device of this kind, there is a tape loading device for use in video tape recorders (VTRs). Taking an example of this tape loading device, the following discussion is conducted.
The tape transportation systems for VTRs have conventionally had their form almost generally standardized according to the type of VTR. With the recent trend of reducing the size of the VTR as a momentum, however, development of new tape transportation systems has become prosperous. One of them is exemplified in FIG. 1.
FIG. 1 is a top view of an example of the above-described recently developed tape transportation system for the VTR. In the figure, 51 is a rotary head cylinder having a rotary head on the outer periphery thereof. Movable guide posts 53a and 53b constitute a first guide post unit 53. Another movable guide posts 55a and 55b constitute a second guide post unit 55. A magnetic tape T from a supply reel 71 is transported to a take-up reel 72 through a path defined by the aforesaid two units 53 and 55, fixed guide posts 73 to 77, another movable guide post 78, a capstan 79, a pinch roller 80 movable together with the movable guide post 78, and a tape tension control pin 81.
When to load the tape T in such a predetermined path, the first and second movable guide post units 53 and 55 pull the tape T out of an opening portion of the cassette (not shown) which contains both reels 71 and 72. Having reached the illustrated position, they are arrested and held stationary by catching members (not shown).
In the loaded position, the training of the tape T around the cylinder 51 must be conditioned with the height of the tape T in such a fashion that it is raised toward the entrance, and then lowered to the same level as the take-up reel 72. Such a tape loading method is advantageous at reducing the height of the VTR. So, this method is employed in the tape transportation system of FIG. 1.
In this type of system, the duty of giving the tape T a lifting vector is put on the second guide post unit. It is, therefore, very important for the movable guide posts 55a and 55b to maintain stable the running of the tape T. Hence, the catching of them should be so rigorous as to ensure the designed accuracy of the position and inclination of the tape T.
FIG. 2 illustrates the construction and arrangement of the essential parts of a loading device for establishing the running path in the transportation system of FIG. 1. In the figure, 51 is the rotary head cylinder. The loading device includes a first loading ring 52, the first guide post unit 53 having the movable tape guide posts 53a and 53b provided therein to move along with that unit 53, a second loading ring 54, the second guide post unit 55 having the movable tape guide posts 55a and 55b provided therein to move along with that unit 55, a loading motor 56, a pinion 56a fixedly mounted on the output shaft of the loading motor 56, a gear 57 meshing with both of the pinion 56a and an outer gear of the first loading ring 52, another gear 58 meshing with both the gear 57 and an outer gear of the second loading ring 54, and two catchers 59a and 59b for the first and second guide post units 53 and 55 respectively. T is the magnetic tape.
In operating the device of such construction, when the loading motor 56 rotates, the first loading ring 52 is rotated through the pinion 56a and gear 57, and the second loading ring 54 is rotated a lesser angle or more slowly than the first loading ring 52 in the same direction through the speed reduction of the gears 57 and 58. When the loading is complete, the catchings of the first and second guide post units 53 and 55 by the catchers 59a and 59b respectively occur simultaneously.
This catching is carried out with the guide post units 53 and 55 being pressed against the catchers 59a and 59b by the charged force of springs 61 and 60, respectively.
In the above-described conventional type of loading device, in order to move the first and second guide post units 53 and 55, use is made of two loading rings 52 and 54 which are drivenly connected through the respective individual gears 57 and 58 to the common loading motor 56. Further, they are moved in different ways from each other. Also, during the movement of both guide post units 53 and 55, it is, in general, the first guide post unit 53 that has to be moved in its axial direction. For this purpose, there is provided a guide rail. On the other hand, in order to bring the second guide post unit 55 into abutting engagement on the catcher 59b, it is necessary for it to move away from the second loading ring 54. So, the second guide post unit 55 too has to be moved. In conclusion, the mechanism for operating these or first and second guide post units 53 and 55 is required to have two functions of differentiating their rotative and guiding movements from each other at a time, giving rise a problem that a desired reduction of the size and weight of the device can not be achieved.
In such a configuration, it is difficult to make smaller the diameters of the loading rings 52 and 54. To impart to the mechanism a furthermore function of controlling the relative phases of the two loading rings 52 and 54, the complexity of structure of that mechanism is increased. Thus, the problem for minimizing the size and weight is worsened.
If the aforesaid phases are not adjusted accurately when the first and second guide post units are caught, the good balance between the bias forces on them is broken.
Another problem for minimizing the weight of the device arises from the involvement of an increased number of parts, since the above-described conventional type of loading device is necessarily included with a guide member for directing the second guide post unit 55 to the catcher 59b when the catching is about to occur, a mechanism for moving that guide member to its operative position when the second guide post unit 55 nears it, and another mechanism for pressing the second guide post unit 55 against the catcher 59b.
Further, the above-described loading device, because of the necessity of charging the springs 60 and 61 at the time of catching, suffers from an excessive load on the loading motor. For this reason, as the motor 56, use has to be made of a large-size, expensive one.